Boiler construction



May 6, 1930. R. DOHERTY BOILER CONSTRUCTION Filed Feb. 24, 1925 I/w/E/v70/9 Russ/5L1. DOHE/PT) By I Patented May 6, 1930 PATENT errrcs RUSSELLDOHERTY, OF OAK PARK, ILLINOIS BOILER CONSTRUCTION Application filedFebruary 24, 1925. Serial No. 11,223.

The present invention has to do with boiler construction and has for itsobject the pro vision of improved means for obta1n1ngcomplete combustionin a boiler by providmg unique means for the admisslon of supplementalair thereto.

The invention contemplates the admission of additional air to thefirebox or fines in order that the oxygen of the air may combine withthe combustion vapors and produce an admixture insuring the completecombustion of the fuel, and the highest heat obtainable. The device isintended to act as a smoke preventive in that enough supplemental air isintroduced, and at the proper place, to completely oxidize the carbon ofthe fuel.

' Among the objects of the invention are the following The provision ofa boiler having a plurality of separated throat passages fromthefirebox; i i j An unique arrangement whereby to provide at all times fora free flow of combustion vapors between the firebox and fines;

The provision of a main throat passage and an auxiliary passage forcombustion vapors intermediate the firebox and fine, such latter passagehaving means for admitting supplemental air adjacent or approximate suchpassage;

The addition to a boiler of an auxiliary throat passage superposed uponthe normal throat passage thereof and having means for co-minglingheated air with the combustion vapors during their passage from thefirebox to the lines; i

A novel boiler construction providing for two or more throat passagesintermediate the firebox and fines, each passage providing means forco-mingling pro-heated air with the combustion vapors.

These, and such other objects as may hereinafter appear, are obtained bythe novel construction of the boiler, the combination of the elementstherein, and in the arrangement of the parts thereof. For a completeunderstanding of the invention, reference should be had to theaccompanying drawing, illustrative of embodiments of the invention, andin which Figure l is a longitudinal section through the improved boiler.

Figure 2 is a transverse section therethrough on the line 22 of Figure1, a part of the boiler section structure being broken away to provide abetter detail view.

Figure 3 is a fragmentary view, similar to Figure 2, showing a modifiedtype of boiler construction.

Figure 4 is a similar view of another modified form of the invention.

Like reference characters are used to designate similar parts in thedrawing and in the specification which follows.

The invention is adapted for use upon furnaces and boilers, but forpurposes of illustration a boiler is shown. The boiler illustrated inFigure 1 includes a plurality of ho].- low water containing sections 1,bolted together in the customary way. The usual end sections 2 and 3,are connected to the adjacent sections 1. The front section2 includesvarious doors and dampers as is usual, and the rear section 3 has atake-off 4. Sections 2 and 3 have conventional water spaces, and all ofthe water spaces in sections 1, 2, and 3 are in communication as isusual inboiler construction. i

Intermediate two of sections 1 and properly spaced between ends 2 and 3,is a section 5 in which the features of the invention are embodied. Thewater spaces in section 5 form a part of the communicating water spacesof the boiler, and are designated 5.

By reference to Figure 2, in conjunction with Figure 1, the constructionof sections 1 and 5 employed may be readily understood. Flue spaces 6 insaid sections 1 and 5 provide for the passage of the combustion gasesforwardly through the boiler and a passage 7 in said sections providesfor the transfer of such combustion vapors backwardly through the boilerand out through the takeoff 4 to the chimney. A throat passage 8,intermediate the firebox and a bridge wall 9 in a long boiler, or therear section 3 in a short boiler, allows for the transfer of combustionvapors from the firebox to the fines 6. Said passage 8 may be topped bya transverse air box 10 having a plurality of openings 11 whereby air isadmitted downwardly into the passage 8. Box 10 may comprise a separatecasting as shown in Figure 2, or be combined in a single casting havingtwo lateral passages as shown in Figure 1. Said box 10 has openings inthe sides of section 5, the air admitted through said box beingsupplemental to that admitted through the various doors and dampers insection 2, and through the grate, designated 8*. Grate 8 preferablyextends. from the front of. the boiler tothebridge wall 9, in longboilers and to the rear wall 8 in short boilers.

The transverse air boxor channel 10may.

Y be water cooled as shown in Figure 1 in order to. maintain thetemperature of the supplemental air admitted therethrough. below thetemperature of the wallsof the air box exposedtothe direct flame, andalso to provide protection. for the air box 10 which otherwise wouldshortly burn outbecause of. the intense heat to which the fire box isexposed.

In. the arch. section 5, immediately above the throat passage 8, is asecond or auxiliary throat passage 12. which may be circular as shown inFigure 2, rectangular as. shown in Figure 3,01- of any other preferredshape. Two; circular. throat passages 12 are shown. in. the sectionillustrated inFigure Any numer i; Openings. 12 may be'usedzto. meetrequirements The throat passage 12 is the central aperture throughamember or vessel having parallel walls, the external wall 13 of suchvessel being abuttedor engaged by the lirehrickorfi-re clay ll builtintothe section '5 about. said apertured.memberand above the air way 10. Theinternal wall. 15 of said vessel or apertured. member has. apluralityof. ducts 16 opening inwardly. Said open.- ings 1 6, are generallyofigreatest area at. the top of the vessel as. shown or farthest from theair intake, The width of passages 16. decreases as the bottom of thevapertured: member is approached, when the; air box is a h ott m, but wnthe air box is at the top, this, condition is, reversed, Sometimes a.sh ort section. of- Ithe the; wall 15 adjacent the air box is completelyclosed to prevent ad.- mission of air at thispart of; the throat passage12, for thereis astrong suction from the combustion gases tending topreventequal distribution of air around, the wholeof throat passage 12unless. sucha measure asthisisemlayed.

The apertured membenis sox disposed insection that it may readily beconnected to or joined to a transverse air passage 17 having dampercontrols 18 at the external extremities thereof as shown in Figure 2.Such dampers 18 may be actuated by any .of the means common to dampercontrol. In Figure 1 a single casting is shown for forming passages and17.

Means may also be provided for water cooling the air admitted throughthe passage 17 as shown. As previously indicated, the purpose of havinggraduated openings 16 about throat passage 12. is to. insure an evendistribution of supplemental air around the throat passage 12 forcombination with the combustion vapors passing therethrough. Were theopenings 16 all of the same size, more air would be drawn into theaperture from those passages. 16 immediatelyadjacent the air shaft 17and an unequal distribution of heated air about throat passag 12 wouldthus. result.

A. single passage could, of course, be utilized to concurrently providefor the admis sion of air into, the throat passages 8 and 12 and thismay be done when the sections? are of such dimensionsthat. it is;desirable to do to save space. A. pa ition therebetween is desirablehowever. The particular position of the passage 17 here disclosed is notthe precise position which it must occupy, and, as previously remar hit;may be abov throat passage 12. The configuration of the tlu'oat passagem y, be. v ried. o uit d fte-rent constructions in. boil rs, ls to acommodate itself to fu nace. constructions. By. the structure hi h; i hedi cl se the combustion gases formed in thefireboxmay re ets h fluepaces by one O -tw ou se hroatpassage r h oat passag 12.- Two;

such throat passages are highly desirable when a; very hot fire isrequired for these insure suff cient draft and; rapid and completecombustion.

In Figure 41., two. throat passages 12 are shown, each adapted to besupplied by a transverse air box 17. Such a structure is desirable whenthe charactenof .fuelrequires arge olume of; supplemental air, o theboiler is of such width that it requires several passages.

It is very truethatmost janitors and. caretakers are not familiar. with.the principles underlying, the proper; firing of boilers, and, this lackof knowledge has. often. caused a furnace to be condemned when, as amatter of; fact, t he fault resided wholly in the person firing theboiler. When a fire isbanked high,there is aninadequate opening throughthroat passage 8 for the combustion vapors to travel. The throat passage8 is sometimes completely closed. by f-uelpoorly placed, and will permitof the passage of" practically no combustion vapor. This conditionmaycause violent explosions. It is self apparent that no fireman,however negligent, could obstruct the throat passage or throat passages12, and a proper draft through the boiler or furnace at all times isthus assured when an auxiliary throat passage such as I have describedis employed.

In order to obtain the highest efficiency for a fire, and to produce allof the heat which a fuel can give off there must be sufiicient air forcomplete combustion of such fuel. Experiment has demonstrated that theaverage boiler construction provides insufiicient air to completelyoxidize the fuel. It is almost invariably true that enough air can notbe admitted through the grate 8 for complete oxidation. F or this reasonboilers have been designed with the purpose in view of providingsupplemental air in the combustion chamber. Because improperly designedand the air duct or ducts was not properly placed, most of theseproposed constructions have been failures.

The present invention is for the purpose of admitting to the combustionchamber such supplemental air as is necessary to provide for a completecombustion of all the fire gases, and concurrently to control thedistribution of such air, also, to admit such air at a temperature thatit will readily combine with the aforementioned combustion vapors. Allof these objects are attained by the structure illustrated.

This is accomplished, in part, by providing two throat passages andsupplying the uppermost with a source of supplemental air, it beingoptional whether the lower throat passage has a source of added air.Further, the desired result is obtained by extending the grate 8 to thebridge wall 9, or beyond the arched section 5. The gases reaching throatpassage 12 from the forward section ofthe fire box are underfed inoxygen. From passages 16 oxygen is supplied.

Unless the gases are ignited in the presence of the added supply ofoxygen, and subse quent to passing through throat passage 12, the effectof the supplemental air may be lpst. The burning fuel upon the grate 8to the rear of arched section 5 willusually provide the flame or highheat necessary to ignite the gases which have passed through throatpassage 12. Even when the fuel back of throat passage 8 is not luminous,the heat therefrom and the reflected heat of bridge wall 9 is ordinarilysufficient to cause ignition of the aircharged combustion vapors.

The device may be modified to accommodate oil burners, and it is quitemanifest that the arrangement may be adapted to furnaces and to boilersother than the type illustrated. Means for protecting the air box may bein the form of a water back, fire clay, or fire brick, or fire resistingmaterial.

I claim:

1. In a boiler having a throat passage and throat passages.

2. In a furnace, a firebox, a grate therein, a bridge wall abutting therear portion of said grate, a water curtain depending from the roof ofsaid firebox and in a position in advance of said bridge wall andforming a narrow transverse throat passage between said grate and thelower portion of said water curtain, said curtain having a second throatpassage formed above said narrow transverse throat passage, and meansfor admitting a volume of supplemental air in a position to combine withthe gases passing through said upper throat passage, and separate meansfor admitting a volume of supplemental air to said narrow transversethroat passage.

3. In a furnace, a firebox, a grate therein, a bridge wall abutting therear portion of said grate, a water curtain depending from the roof ofsaid firebox and in a position in advance of said bridge wall andforming a narrow transverse throat passage between said grate and thelower portion of said water curtain, said curtain having an additionalthroat passage therethrough and above said narrow transverse throatpassage, and means for admittin a volume of supplemental air in aposition to combine with the gases pass ing through said additionalthroat passage, separate means for admitting a volume of supplementalair to said narrow transverse throat passage, and means for limiting thetemperature of the supplemental air admitted to said throat passages.

4. A furnace as defined in claim 2, wherein the air to said throatpassages is admitted through parallel intakes in said water curtainwhereby the temperature of said air is limited by the temperature of thewater in said water curtain.

In a boiler, the combination with a fire box, of a plurality of throatpassages arranged side by side and superposed above said fire box, meansfor admitting a natural draft of air beneath and through said fire box,independent passages communicating with said fire box and said throatpassages for conducting supplemental air thereto, and boiler waterchambers in the path of said supplemental air passages to preheat theair prior to its introduction within said boiler.

6. In a boiler, the combination with a fire box, of a plurality ofthroat passages associated with said fire box, means for admitting anatural draft of air beneath and through said fire box, independentpassages communicating with said fire box through said throat passagesfor conducting supplemental air to said fire box, boiler water chambersin the path of said supplemental air passages to prheat the air; priorto its introduction Within said boiler and Valve control means. for

said supplemental air supplyingpassages.

7. Ina boiler having a grate and a bridge .wall, a throat passage belowsaid Wall and extending its Width there being aseri-es' of horizontallymouthed air ducts in said Wall opening into said throat passage, asecond throat passage through said wall andof less than its Width, therebeing a series, of air ducts in said Wall and having their months atanangle one to another and opening into said secondpassage, and.independent air intakes to each seriesof saidair ducts.

RUSSELL DOHERTY.

